Buggy code:
public interface WebProtegeClientBundle extends ClientBundle { public static final WebProtegeClientBundle BUNDLE = GWT . create ( WebProtegeClientBundle . class ) ; @ Source ( "protege-logo.png" ) ImageResource webProtegeLogo ( ) { } @ Source ( "about.html" ) TextResource aboutBoxText ( ) { } @ Source ( "feedback.html" ) TextResource feedbackBoxText ( ) { } @ Source ( "class.png" ) ImageResource classIcon ( ) { } @ Source ( "property.png" ) ImageResource propertyIcon ( ) { } @ Source ( "property.png" ) ImageResource objectPropertyIcon ( ) { } @ Source ( "property.png" ) ImageResource dataPropertyIcon ( ) { } @ Source ( "annotation-property.png" ) ImageResource annotationPropertyIcon ( ) { } @ Source ( "datatype.png" ) ImageResource datatypeIcon ( ) { } @ Source ( "individual.png" ) ImageResource individualIcon ( ) { } @ Source ( "literal.png" ) ImageResource literalIcon ( ) { } @ Source ( "link.png" ) ImageResource linkIcon ( ) { } @ Source ( "iri.png" ) ImageResource iriIcon ( ) { } @ Source ( "number.png" ) ImageResource numberIcon ( ) { } @ Source ( "date-time.png" ) ImageResource dateTimeIcon ( ) { } @ Source ( "download.png" ) ImageResource downloadIcon ( ) { } @ Source ( "trash.png" ) ImageResource trashIcon ( ) { } @ Source ( "warning.png" ) ImageResource warningIcon ( ) { } @ Source ( "eye.png" ) ImageResource eyeIcon ( ) { } @ Source ( "eye-down.png" ) ImageResource eyeDownIcon ( ) { } @ Source ( "note.png" ) ImageResource noteIcon ( ) { } @ Source ( "user.png" ) ImageResource userIcon ( ) { } @ Source ( "alert-icon.png" ) ImageResource alertIcon ( ) { } @ Source ( "message-icon.png" ) ImageResource messageIcon ( ) { } @ Source ( "question-icon.png" ) ImageResource questionIcon ( ) { } @ Source ( "numbered-list.png" ) ImageResource numberedListIcon ( ) { } @ Source ( "bulleted-list.png" ) ImageResource bulletedListIcon ( ) { } @ Source ( "link-black.png" ) ImageResource linkBlackIcon ( ) { } @ Source ( "progress.gif" ) ImageResource progressAnimation ( ) { } @ Source ( "comment.png" ) ImageResource commentIcon ( ) { } @ Source ( "comment-small.png" ) ImageResource commentSmallIcon ( ) { } @ Source ( "comment-small-filled.png" ) ImageResource commentSmallFilledIcon ( ) { } @ Source ( "edit.png" ) ImageResource editIcon ( ) { } <START_BUG> @ Source ( "webprotege.css" ) <END_BUG> WebProtegeClientBundle . WebProtegeCss style ( ) ; public static interface WebProtegeCss extends CssResource { String webProtegeLaf ( ) { } String formMain ( ) { } String formGroup ( ) { } String formLabel ( ) { } String dlgLabel ( ) { } String formField ( ) { } String warningLabel ( ) { } String classIcon ( ) { } String deprecatedClassIcon ( ) { } String classIconInset ( ) { } String objectPropertyIcon ( ) { } String deprecatedObjectPropertyIcon ( ) { } String objectPropertyIconInset ( ) { } String dataPropertyIcon ( ) { } String dataPropertyIconInset ( ) { } String deprecatedDataPropertyIcon ( ) { } String annotationPropertyIcon ( ) { } String deprecatedAnnotationPropertyIcon ( ) { } String annotationPropertyIconInset ( ) { } String datatypeIcon ( ) { } String deprecatedDatatypeIcon ( ) { } String datatypeIconInset ( ) { } String literalIcon ( ) { } String literalIconInset ( ) { } String individualIcon ( ) { } String deprecatedIndividualIcon ( ) { } String individualIconInset ( ) { } String linkIcon ( ) { } String linkIconInset ( ) { } String iriIcon ( ) { } String iriIconInset ( ) { } String numberIcon ( ) { } String numberIconInset ( ) { } String dateTimeIcon ( ) { } String dateTimeIconInset ( ) { } } }

Fix:
@ Source ( "WebProtege.css" )